Sunni Islamist insurgents who control large parts of northern Iraq attacked a town north of Baghdad early today, seizing local government buildings, police and witnesses said.

They said militants in 50 to 60 vehicles stormed the town of Dhuluiya, about 70km (45 miles) north of Baghdad early this morning, taking the mayor’s office and municipal council building and fighting to take control of the police station.

Insurgents led by the al-Qaeda offshoot Islamic State of Iraq and the Levant (Isis) seized swathes of Iraq’s northern and western Sunni Muslim provinces in a two-day offensive last month.

They were pushed back at Dhuluiya on June 14th by soldiers loyal to Prime Minister Nuri al-Maliki’s Shia-led government backed by fighters from the Shia Asaib Ahl al-Haq militia, but fighting has continued and they have taken other towns.

The police and witnesses said local police and tribes were battling the militants in Dhuluiya today. They said four policemen were killed in the fighting, as well as two militants and two civilians.

Insurgents also bombed a bridge linking Dhuluiya to the nearby Shia town of Balad to the west, they said.

Yesterday, gunmen killed at least 33 people, including 29 women, in a raid on two buildings in a housing complex in Baghdad. The gunmen showed up in four-wheel drive vehicles before storming the buildings in the Zayounah neighbourhood in eastern Baghdad, officials said. At least 18 people were wounded.

Meanwhile, Iraq’s parliament have postponed until Tuesday a meeting aimed at agreeing on the formation of a new government because of a lack of consensus, parliamentary officials said today.

Deputies had gathered in parliament for talks intended to agree a prime minister, president and speaker of parliament, three months after Iraq’s parliamentary election. The political impasse has been given added urgency by the Islamist-led insurgency which swept through Sunni provinces of northern Iraq last month and has threatened Baghdad.

Mr Maliki’s opponents accuse him of ruling for the Shia majority at the expense of Sunni and Kurdish minorities, and want him to step aside, but he shows no sign of quitting. His State of Law coalition is the biggest group in the Shia National Alliance grouping.